Cationic adsorption agent

ABSTRACT

A cationic adsorption agent which is obtained by reaction of 
     (a) an amino compound which contains at least one amino group and at least one free or methylolated carboxamide group, with 
     (b) an aminoplast precondensate which does not contain amino groups. 
     The novel adsorption agent is suitable in particular for removing anionic substances, such as acid dyes or reactive dyes, from aqueous solutions, especially from wastewaters.

This is a divisional of application Ser. No. 162,275 filed on June 23,1980, now U.S. Pat. No. 4,316,005, issued Feb. 16, 1982.

The present invention relates to a cationic adsorption agent which issuitable for removing anionic substances from aqueous solutions,especially from wastewaters, e.g. from filtrates, residual liquors ofbleaching or dyeing processes, rinsing and wash waters.

The adsorption agent of this invention is obtained by reaction of

(a) an amino compound which contains at least one amino group and atleast one free or methylolated carboxamide group, with

(b) an aminoplast precondensate which does not contain amino groups.

Component (b) is a compound which contains amide groups but no basicamino groups. Components (a) and (b) together advantageously contain atleast two N-methylolamide groups.

It is particularly advantageous if the adsorption agent is obtained withamino compounds (a) of the formula ##STR1## wherein m is 1 to 5, each ofR₁, R₂ and R₃ independently is hydrogen, lower alkyl which isunsubstituted or substituted by halogen, hydroxyl, lower alkoxy orcyano, or is cycloalkyl, benzyl or the group of the formula ##STR2## orR₁ and R₂, together with the nitrogen atom to which they are attached,denote a 5- or 6-membered heterocyclic radical, preferably pyrrolidino,piperidino, morpholino or piperazino, or, if m is 2, R₂ and R₃, togetherwith the grouping >N--Q--N< which links them, denote a divalent 5- or6-membered heterocyclic radical, especially an imidazolidino orpiperazino ring, or, if m is greater than 2, each R₃, or individualsubstituents R₃, together with the adjacent R₅ and thegrouping >N--Q--N< which links them, also denote a divalent 5- or6-membered heterocyclic radical, especially a piperazino ring; each of Qand Q₁ independently is alkylene of 1 to 8 carbon atoms, X is hydrogenor --CH₂ OH, and Y is hydrogen, lower alkyl or --CH₂ OH.

Preferred amino compounds of the formula (1) are those in which m is 1or 2, namely the monoamino or diamino compounds.

Especially preferred mono- and diamino compounds suitable for use ascomponent (a) are those of the formula ##STR3## wherein m₁ is 1 or 2,each of R₄, R₅ and R₆ independently is hydrogen, lower alkyl, benzyl orthe group of the formula ##STR4## or R₄ and R₅, together with thenitrogen atom to which they are attached, denote a 5- or 6-memberedheterocyclic radical, especially pyrrolidino, piperidino or morpholino,or, if m is 2, R₅ and R₆, together with the grouping >N--Q--N< whichlinks them, denote a piperazino ring, and each of Q₂ and Q₃ is C₁ -C₃alkylene, and X and Y have the given meanings. Amino compounds of theformula (3) in which m₁ is 1, and which contain only a single groupingof the formula (4), are still more preferred. In these compounds, Q₃ ispreferably the ethylene or propylene group, R₄ and R₅ are preferablylower alkyl, Y is especially hydrogen, and X is preferably --CH₂ OH.

In the definition of the radicals of the novel compounds, lower alkyl oralkoxy are usually those groups or group constituents which contain 1 to5, especially 1 to 3, carbon atoms, e.g. methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl or amyl, or methoxy, ethoxy or isopropoxy.

Halogen in connection with all substituents denotes e.g. fluorine,bromine or, preferably, chlorine.

Suitable for use as component (b) are adducts of formaldehyde withmethylolatable amide compounds which do not contain basic amino groups,e.g. ureas, thioureas and amino-1,3,5-triazines.

Suitable urea and thiourea compounds are e.g. urea, thiourea,substituted areas such as alkyl or aryl ureas, alkylene ureas andalkylene diureas such as ethylene urea, propylene urea,dihydroxyethylene urea, hydroxypropylene urea and acetylene diurea, andalso dicyandiamide, dicyandiamidine, urones and hexahydropyrimidones.

Examples of 1,3,5-aminotriazines which may be mentioned are: melamineand N-substituted melamines, such as N-butyl-melamine,N-trihalogenomethyl melamines, triazones, ammeline, guanamines, e.g.benzoguanamine, acetoguanamines, diguanamines, and guanidines.

Suitable aminoplast precondensates are both primarily mono-molecularcompounds and higher condensed products.

Both completely methylolated and only partially methylolated compounds,which can also be etherified, also yield useful products.

Preferred methylol compounds are those of the ureas andamino-1,3,5-triazines specified above. Of these compounds, N-methylolureas and N-methylol melamines are especially preferred. It is alsopossible to use partial ethers of such methylol compounds, e.g. withalkanols containing 1 to 4 carbon atoms, such as methanol, ethanol,n-propanol or n-butanol.

Specific aminoplast precondensates (b) are e.g.: N,N'-dimethylol urea,methylol urea, N,N'-dimethylol urea dimethyl ether, N,N'-tetramethylolacetylene diurea, N,N'-dimethylol ethylene urea, N,N'-dimethylolpropylene urea, 4,5-dihydroxy-N,N'-dimethylol ethylene urea,N,N'-dimethylol-5-hydroxypropylene urea,4-methoxy-5,5-dimethyl-N,N'-dimethylolpropylene urea,N,N'-dimethylol-5-oxapropylene urea,4,5-dihydroxy-N,N'-dimethylolethylene urea dimethyl ether, dimethylolmelamine, trimethylol melamine, tetramethylol melamine, hexamethylolmelamine, hexamethylol melamine pentamethyl ether, pentamethylolmelamine dimethyl or trimethyl ether, hexamethylol melamine hexamethylor hexaethyl ether. Of these compounds, N,N'-dimethylol urea and tri- tohexamethylol melamines are especially preferred. It is also possible touse mixtures of these methylolated urea and melamine compounds.

The cationic adsorption agent of the present invention is obtained byreacting

(a) an amino compound which contains at least one amino group and atleast one free or methylolated carboxamide group, with

(b) an aminoplast precondensate which does not contain amino groups orwith its production mixture.

The reaction is preferably conducted in a neutral or acid medium, e.g.at a pH value from 2 to 7 and advantageously at a temperature in therange from 20° to 200° C., preferably from 50° to 180° C. and mostpreferably from 60° to 120° C.

It is preferred to employ a catalyst. Suitable catalysts are organic orinorganic peroxides or persalts, e.g. barium peroxide, dicumyl peroxide,di-tert-butyl peroxide, diacetyl peroxide, dibenzoyl peroxide, benzoylperoxide, benzoyl acetyl peroxide, dilauryl peroxide, hydrogen peroxide,percarbonates such as potassium percarbonate, persulfates such asammonium persulfate, or perborates.

Preferred catalysts, however, are inorganic and/or organic acids oranhydrides or salts thereof, e.g. sulfurous acid, sulfuric acid,sulfamic acid, phosphoric acid, hydrochloric acid, chloroacetic acid,maleic acid or the anhydride thereof, ammonium chloride, ammoniumnitrate, ammonium phosphate, ammonium acetate or aluminium sulfate.Sulfamic acid is especially preferred.

The adsorption agent of the present invention is advantageouslysynthesised from 1 mole of component (a) and 0.2 to 10 moles, preferably0.2 to 3.5 moles and, most preferably, 0.5 to 2 moles, of component (b).

The reaction products accordingly contain as a rule 1% by weight,preferably 2 to 6% by weight, of basic nitrogen. The total nitrogencontent, which also comprises the amide nitrogen, is usually at least10% by weight, preferably 15% to 30% by weight.

The adsorption agent of the present invention is suitable in particularfor removing anionic substances from aqueous solutions, especially fromwastewaters, and its efficiency is substantially greater than that ofconventional adsorbents. Compared with known agents, e.g. activatedcarbon, the novel adsorption agent is distinguished in particular by apronounced adsorptive capacity for substances, especially anionicsubstances, which are dissolved or dispersed in water.

Accordingly, the present invention also provides a process for removinganionic substances from aqueous solutions, which process comprisesbringing said aqueous solutions into contact with the novel cationicadsorption agent.

This process is suitable in particular for purifying aqueous liquorswhich contain organic anionic substances and mixtures thereof. It ispossible in particular to remove anionic dyes, fluorescent whiteningagents, dyeing or textile assistants, surfactants, tannins and mixturesthereof from the wastewaters to a satisfactory degree. In the practiceof this invention, wastewaters which contain mixtures of anionic dyesand anionic assistants can be successfully purified.

On account of the broad applicability of the adsorption agent used inthis invention, it is possible to meet the nowadays ever more urgentdemand for saving fresh water by a partial to complete recirculation ofresidual or waste liquors. Independently of the apparatus used, theseare principally the wastewaters of the dyestuff, fibre manufacturing,textile, paper, and leather industry, which occur in connection withdyeing, bleaching, washing and tanning processes. In the case of adyeworks, these wastewaters can originate from the conventional dyeingmachines used for the dyeing of loose fibrous material, tops, yarn, andwoven and knitted fabrics, and also from cleaning machines, e.g. anopen-width washer.

The purification of the wastewaters is advantageously carried out in thetemperature range from 2° to 150° C. with the preferred range, however,being from 10° to 100° C., especially 20° to 70° C. If desired, it isalso possible to purify the wastewaters under pressure or in vacuo. ThepH of the liquor can vary within wide limits, for example from 2 to 12.Depending on the nature of the adsorption agent employed, pHadjustments, for example to a value of 2 to 9, in particular of 3 to 8,can simplify and speed up the purification process.

The treatment of the wastewaters can be carried out discontinuously,semi-continuously or continuously. In principle, the following threeprocesses are suitable within the scope of the invention:

(a) the stirring process, in which the water to be purified is stirredin a vessel with the adsorption agent and then the two are separated;

(b) the fluidised bed process, in which the adsorption agent is kept insuspension through the stream of the liquor to be purified;

(c) the fixed bed process, in which the liquor to be purified isconducted through a filter-like adsorption agent.

If the last of these three process variants, process (c), is applied,then the following three alternatives with respect to the apparatusemployed are especially suitable:

1. The treatment apparatus, e.g. dyeing appliance, is firmly connectedto the filter device.

2. The adsorber device is movable and can be coupled as required withany treatment apparatus.

3. The wastewaters originating from the treatment apparatus are combinedin a suitable container and then jointly passed through the adsorptionmaterial.

If desired, the cationic adsorption agent to be employed in the practiceof this invention can be mixed with other ion exchangers or adsorbents,e.g. activated carbon and/or other known filtration aids, e.g. peat,kieselguhr or diatomaceous earth. For example, the activated carbon maybe added to the novel adsorption agent in an amount of 2 to 95% byweight, preferably 10 to 70% by weight, based on the weight of thecationic adsorption agent.

Possible dyes which can be removed from wastewaters in the practice ofthis invention are anionic dyes which are both soluble and dispersiblein water, and fluorescent whitening agents. In particular, the processof the invention is suitable for removing water-soluble anionic dyes orfluorescent whitening agents.

The anionic dyes are dyes whose anionic character is dependent on metalcomplex formation alone and/or on the acid substituents which impart thewater-solubility. Suitable acid substituents which impart thewater-solubility are carboxylic acid groups, phosphoric acid groups,acylated sulfonic acid imide groups, such as alkyl- or aryldisulfimidegroups or alkyl- or arylcarbonylsulfimide groups, alkyl- or arylimidegroups, sulfuric acid esters groups and especially sulfonic acid groups.

The anionic dyes can belong to a variety of different types of dye. Asexamples there may be mentioned oxazine, triphenylmethane, xanthene,nitro, acridone, stilbene, perinone, naphthoquinone-imine,phthalocyanine, anthraquinone and azo dyes. These last mentioned dyescan be metal-free, metallisable or metal-containing monoazo, disazo andpolyazo dyes, including formazane dyes, in which the metal atom forms a1:1 or 1:2 complex, especially 1:2 chromium or 1:2 cobalt complexeswhich contain two similar or two different molecules of azo dyecomplexed to a chromium or a cobalt atom. These dyes can also contain inthe molecule reactive groups, i.e. groups which form a covalent bondwith the fibrous material to be dyed.

The novel adsorption agent is suitable not only for decolourisingresidual liquors of the dyestuffs industry and those emanating from thedyeing of textiles, paper and leather, but is also most useful when itis a matter of eliminating residues of anionic fluorescent whiteningagents from wash and bleach liquors.

The fluorescent whitening agents can belong to any class of whitenercompounds. The anionic fluorescent whitening agents are in particularstilbene compounds, pyrazolines, dibenzoxazolyl or dibenzimidazolylcompounds or naphthalimides which contain in the molecule at least oneacid group, for example a carboxylic acid group or preferably a sulfonicacid group, and which can be fibre reactive.

A further advantage of the adsorption agent of this invention is that,besides removing the dyes, it permits also at least a partialelimination of non-ionic and anionic surfactants and textile and dyeingassistants, as well as phosphates, from aqueous waste liquors. Suchassistants are described in more detail in"Tenside-Textilhilfsmittel-Waschrohstoffe" by Dr. Kurt Lindner(published by Wissenschaftliche Verlagsgesellschaft Stuttgart, 1964).

The cationic adsorption agent can also be effective in the eliminationof anionic synthetic tannins, especially tannins that carry one or moresulfo groups in the molecule. A more detailed description of thesecompounds can be found e.g. in "Ullmans Encyclopadie der technischenChemie", Vol. 11, pp. 595-598. The cationic adsorption agent can also beused as general anion exchanger.

Appropriate choice of the adsorption agent makes it possible to extractup to 100% of the impurities from the wastewaters. It is possible toachieve retardant effects of up to 50 g of waste matter, i.e. dye,fluorescent whitening agent, assistant, detergent, tannin, per 100 g ofadsorption agent.

It is preferred to decolour wastewaters having a dye concentration of0.01 to 1 g/l. Whenever a complete docolourisation or removal of thewaste substance cannot be accomplished by a single treatment of thewaste liquor with the adsorption agent, it is advisable to repeat thepurification procedure.

After adsorption of the impurities, the adsorption agent can be easilyseparated from the purified wastewater. It has a high solids content andcan therefore be incinerated direct without drying. If desired, theadsorption agent can also be regenerated with the aid e.g. of a diluteaqueous sodium hydroxide solution.

The invention is illustrated by the following Examples, in whichpercentages are by weight.

EXAMPLE 1

4.8 g of N,N'-dimethylol urea are added to 8.6 g of a 40% aqueoussolution of the compound of the formula

    (C.sub.2 H.sub.5).sub.2 N--CH.sub.2 CH.sub.2 --CONH--CH.sub.2 OH (11)

whereupon the mixture is adjusted to a pH value of 3 with conc.hydrochloric acid. With efficient stirring, the acid mixture is thenheated to 150° C. and kept at this temperature for 15 minutes, duringwhich time water is removed and the reaction mass becomes hard. Afterfurther condensation for 15 hours, 8 g of a condensation product with anitrogen content of 22.4% are obtained.

EXAMPLES 2 TO 9

The procedure described in Example 1 is repeated, using the startingmaterials listed in columns 2 and 3 of Table 1 in the specified amounts,and at the pH values indicated in column 4. Reaction products with thenitrogen content indicated in column 5 are obtained.

                  TABLE 1                                                         ______________________________________                                                                                    N                                 Ex-                                         con-                              am-        Aminoplast                       tent                              ple  g     precondensate                                                                             g    Amino compound                                                                            pH  in %                              ______________________________________                                        2    7.2   N,N'--dimeth-                                                                             8.6  formula (11)                                                                              3   18                                           ylol urea                                                          3    2.4   N,N'--dimeth-                                                                             8.6  formula (11)                                                                              7   22.4                                         ylol urea                                                          4    4.8   N,N'--dimeth-                                                                             2.8  2-N,N--diethyl-                                                                           3   23.1                                         ylol urea        aminopropionate                                   5    4.8   N,N'--dimeth-                                                                             4    N,N'--diaceto-                                                                            3   27.1                                         ylol urea        amidopiperazine                                   6    4.8   N,N'--dimeth-                                                                             2.3  N,N'--β-dipropion-                                                                   3   21.7                                         ylol urea        amidopiperazine                                   7    4.8   N,N'--dimeth-                                                                             3.8  N--β-propionamido-                                                                   3   25.8                                         ylol urea        piperidine                                        8    4.8   N,N'--dimeth-                                                                             2.28 N,N--diethyl-N',                                                                          3   21.7                                         ylol urea        N'--β-dipropion-                                                         amidopropyl-                                                                  diamine                                           9    4.3   N,N',N"--tri-                                                                             8.6  formula (11)                                                                              3   25.3                                         methylol                                                                      melamine                                                           ______________________________________                                    

EXAMPLE 10

3.4 g of 35.7% formaldehyde and 2.4 g of urea are added to 8.6 g of a40% aqueous solution of the compound of the formula (11). The mixture isthen adjusted to pH 3 with conc. hydrochloric acid. With efficientstirring, the acid mixture is then heated to 150° C. and kept at thistemperature for 15 minutes, during which time water is removed and thereaction mass become hard. Further condensation for 15 hours yields acondensation product with a nitrogen content of 17.2%.

EXAMPLE 11

With stirring, 330 g of N,N'-dimethylol urea area added to, and mixedwith, 537.5 g of a 40% aqueous solution of the compound of the formula(11) which has been adjusted to pH 4. The milky mixture obtained isstirred and heated to 60° C., then 23 g of 15% sulfamic acid are added,whereupon the temperature rises to 68° C. in the course of 8 minutes andthe reaction mixture congeals. The reaction mass is then heated toreflux temperature (98° C.), in the course of which stirring can beresumed after 10 minutes because of melting on the glass wall of thereactor. Further condensation for 1 hour yields a highly viscous crudecondensate, which is poured onto metal drying plates. The water isremoved at 90° C. and the residue is dried at 110° C. for 12 hours andthen purified by washing with water, affording 390 g of a pure productwith a nitrogen content of 25.8%. The dry powder is comminuted in across beater mill to a granular size smaller than 100μ. Similarly goodadsorption agents with a nitrogen content of 18 to 25% are obtained byreplacing sulfamic acid as catalyst by ammonium nitrate, ammoniumphosphate or ammonium chloride, and dimethylol urea by trimethylolmelamine dimethyl ether, hexamethylol melamine, N,N'-dimethyloluronedimethyl ether or hexamethylol melamine hexamethyl ether.

EXAMPLES 12 TO 21

A stirred reactor is charged with 5 liters of a red residual liquorwhich has been adjusted to pH 3 or 7 and which still contains 100 mg/lof the dye of the formula ##STR5## in dissolved form. The dye liquor isheated to a temperature of 50° C. and, in each test, 0.5 g of one of theanion exchangers prepared according to Examples 1 to 10 is added inpowder form. A sample is taken on each occasion after an adsorption timeof x minutes and filtered through a folded filter. The percentagediscolouration of the filtrate reported in Table 2 is determined.

                  TABLE 2                                                         ______________________________________                                                Adsorbents                                                                    prepared                                                                      according to      Adsorption time                                                                         Discolour-                                Example Example    pH     in minutes                                                                              ation in %                                ______________________________________                                        12      1          7      60        65.8                                      13      2          7      60        21.6                                      14      3          7      60        27.2                                      15      4          3      60        46.5                                      16      5          3      60        32                                        17      6          3      60        18.9                                      18      7          3       5        80.5                                      19      8          3      60        15.2                                      20      9          7      60        6.9                                       21      10         7      60        21.5                                      ______________________________________                                    

EXAMPLE 22

In a glass beaker, a solution of 500 mg of a dye of the formula (100) in500 ml of water is adjusted to pH 7 with a sodium carbonate solution.With stirring, 500 g of the condensation product of Example 11 are addedat 50° C. to this dye solution and kept at this temperature for 60minutes. The treated solution contains only 125 ml of dye, correspondingto 75% decolouration. The dye precipitate is collected by filtration.The moist filter cake has a solids content of 50% and can be incinerateddirect without further evaporation.

What is claimed is:
 1. A process for the removal of an anionic substancefrom an aqueous solution, which process comprises bringing said solutioninto contact with a cationic adsorption agent which has been obtained byreaction of(a) an amino compound which contains at least one amino groupand at least one free or methylolated carboxamide group, with (b) anaminoplast precondensate which does not contain an amino group, in aratio of 1 mole of component (a) per 0.2 to 10 moles of component (b),in an aqueous medium at a pH value between about 2 and
 7. 2. A processaccording to claim 1, wherein the anionic substances are anionic dyes,fluorescent whitening agents, textile or dyeing assistants, surfactants,tannins or mixtures thereof.
 3. A process according to claim 1, whereinthe removal of the anionic substances is carried out in the temperaturerange from 2° to 150° C.
 4. A process according to claim 1, wherein theremoval of the anionic substances is carried out by the stirring orfixed bed method.
 5. A process according to claim 1, wherein thecationic adsorption agent is mixed with activated carbon.
 6. The processof claim 1, wherein the component (a) of the adsorption agent is anamino compound of the formula ##STR6## wherein m is 1 to 5, each of R₁,R₂ and R₃ independently is hydrogen, lower alkyl which is unsubstitutedor substituted by halogen, hydroxyl, lower alkoxy or cyano, or iscycloalkyl, benzyl or a group of the formula ##STR7## or R₁ and R₂,together with the nitrogen atom to which they are attached, represent a5- or 6-membered heterocyclic radical, or, if m is 2, R₂ and R₃,together with the grouping >N--Q--N< which links them, represent adivalent 5- or 6-membered heterocyclic radical, or, if m is greater than2, each R₃, or individual substituents R₃, together with the adjacent R₃and the grouping >N--Q--N< which links them, also represent a divalent5- or 6-membered heterocyclic radical, each of Q and Q₁ independently isalkylene of 1 to 8 carbon atoms, X is hydrogen or --CH₂ OH, and Y ishydrogen, lower alkyl or --CH₂ OH.
 7. The process of claim 6, whereincomponent (a) of the adsorption agent is an amino compound of theformula (1), wherein m is 1 or
 2. 8. The process of claim 7, whereincomponent (a) of the adsorption agent is an amino compound of formula(1), wherein each of R₁, R₂ and R₃ independently is hydrogen, loweralkyl, benzyl or a group of formula (2), or R₁ and R₂ together with thenitrogen atom to which they are attached represent a 5- or 6-memberedheterocyclic radical, or, if m is 2, R₂ and R₃, together with thegrouping >N--Q--N< which links them, is a piperazino ring, and each of Qand Q₁ is C₁ -C₃ alkylene.
 9. The process of claim 8, wherein component(a) of the adsorption agent is an amino compound of formula (1), whereineach of R₁, R₂ and R₃ is hydrogen, lower alkyl or benzyl.
 10. Theprocess of claim 9, wherein component (a) of the adsorption agent is anamino compound of formula (1), wherein m is
 1. 11. The process of claim10, wherein component (a) of the adsorption agent is an amino compoundof formula (1), wherein Q₁ is ethylene or propylene, each of R₁ and R₂is lower alkyl, Y is hydrogen and X is --CH₂ OH.
 12. The process ofclaim 1, wherein components (a) and (b) together contain at least twoN-methylolamide groups.
 13. The process of claim 1, wherein component(b) is a methylolated urea or amino-1,3,5-triazine, each of which isunetherified or etherified.
 14. The process of claim 13, whereincomponent (b) is a N-methylol urea or N-methylol melamine.
 15. Theprocess of claim 14, wherein component (b) is N,N'-dimethylol urea ortri- to hexa-methylol melamine.